A sodium salt hydrate of loxoprofen (generic name: loxoprofen sodium hydrate) has been widely used clinically as a pharmaceutical preparation that has excellent analgesic, anti-inflammatory, and antipyretic effects.
Various kinds of derivatives that retain the excellent analgesic, anti-inflammatory, and antipyretic effects of loxoprofen have been proposed many times so far. For example, derivatives represented by the following formulae A, B, and C are known (Patent Literatures 1 to 3).

Specifically, Patent Literature 1 discloses the compound represented by the above-mentioned formula (A). This compound is reported to have anti-inflammatory, analgesic, and antipyretic effects. Patent Literature 2 also discloses a wide range of derivatives represented formally by the above-mentioned formula (B). However, these derivatives are different from loxoprofen derivatives provided by the present invention.
Furthermore, Patent Literature 3 discloses a wide range of derivatives represented formally by the above-mentioned formula (C). It is reported that these derivatives have an even more potent anti-inflammatory effect and an even more potent analgesic effect than pre-existing acidic nonsteroidal antiphlogistics (acid NSAIDs) represented by aspirin or indomethacin and have very few side effects such as a gastrointestinal tract disorder.
However, specific severity of the side effects such as a gastrointestinal disorder varies depending on respective pharmaceutical preparations, and the severity of injury of the ulcer onset in an alimentary canal, especially in a gastric mucosa, varies greatly.
Therefore, various investigations on the compounds having anti-inflammatory and analgesic effects have been performed so far to separate their pharmacological effects from their side effects. However, no particular achievement has been produced yet.
Under the above-mentioned circumstances, the present inventors investigated loxoprofen derivatives and successfully synthesized a compound that had excellent anti-inflammatory and analgesic effects while avoiding side effects such as a gastrointestinal disorder, and thus accomplished the present invention.